Magic Smoke WILL have Ody VCO boards in about two to three months, for those who can wait (huff, puff, pant). I'm currently testing MKI vs. MKII flavors (huff, pant, wheeze) and we'll have them on a nice blue PCB (pant, gasp, wheeze). Along with some other interesting stuff.

Just wondering what is the status of this Magic Smoke project, and if the Ody VCO will soon be available? Also curious as to what other "interesting stuff" is in the pipe-line?

I second this. Any word? The VCOs on the Ody are my all-time favorites! In the meantime, stockpiling parts...

By the way, in addition to brother303's question, I'd like to know the following: If I send the layout to someplace like guitarpcb.com and have it etched, will it come out correctly? That is, is the drawing scaled correctly (100%) and in the proper format? I've neither etched a pcb, nor had anything etched for me, so this is important.

Is the layout "optimized" or do you think it would be better to wait for Magic Smoke or someone to manufacture the board?

This is the schematic for the Dual VCO (MKIII Odyssey), taken from the Service Manual, maybe you're looking at the original MKI Oddy schematics
Andy

Thank you. I found out over the weekend that the schematic is identical to the ARP Avatar VCO. The only things I have changed are:
2N5910 => I used 2N3906
CA3086 => I used CA3046
I'll try BF245 for the FETs this evening.

regards

Boerge

I've just looked at the datasheets for the FETs, seems you would need to reverse the orientation if using a BF245. I can't find any data on the 2N5910 though, can a 2N3906 just drop straight in, pin for pin?_________________My tunes available here
(check out the new Electro-Funk LP)

Hi:
I just built this dual VCO, I didn't calibrated properly yet, but it seem to be working right.
Thank you AndyR1960 for sharing!!!

I think I have an issue, the RingMod out is mounted over a very high DC offset, about 9V, so the signal swings from 6V to 12V.
Is this normal?
I've checked the circuit and all seems to be OK.
Thank you._________________Sebo
---------------------------------------
My Music:
www.cosaquitosenglobo.com.arwww.myspace.com/cosaquitosenglobo

I built this double VCO board too and, after the usual troubleshooting (I ALWAYS make some mistakes), it works perfectly.

The RingMod output has a strong DC offset in mine too, but from the schematic I would say it's just designed to be so, not an error or a building mistake.
I don't remember the exact amount of DC offset; your '6V to 12V' may well be right. I can measure it tonight and report tomorrow if you like.

All outputs are positive-only; I added output level shifters, but forgot to level-shift this ringmod output, oops!

I modified the board a little in order to have sync input, sync output and LFO option in both oscillators, so that they are now an identical pair; it was easy and worked fine.

This board is just GREAT, tracks well and sounds gorgeous. I am very happy with it. Thank you Andy, thank you ARP, thank you electro.music forum !

Hi Jaba:
Thanks for your reply.
I did level shifters for the output too, and when doing them I discover the DC level of the RingMod out.
If that is a normal behaviour, I just made the level shifter according to that, just want to be sure I didn't make a mistake.
Thank you.

but if you really want your output to be exactly -5V to +5V, then you'll have to change the resistors' values a bit depending on the actual values of your signals, and maybe on your OpAmps offset error too.
I believe that the values shown were intended for converting a 0 to +5V signal into a -5V to +5V one.

If anyone who's built this has bought excess of some or all of these components, I'd be happy to trade or buy your spares. Preferably from one source to save postage, but I don't mind either way, just as long as I get this up and running. Please PM if you can help out.

There was one question about this though, how to match a PNP with a NPN? And if neither the tempco or transistors are thermally coupled (and therefore not actually doing anything), could this be substituted with a fixed metal film & unmatched transistors?

I have a few left over bits and bobs from my build, including the elusive 2N5910 that you can have. I'm away from where I keep my electronics bits until next weekend. If you PM me closer to next weekend to remind me, I can have a look through and see what I can dig out.

I have a few left over bits and bobs from my build, including the elusive 2N5910 that you can have. I'm away from where I keep my electronics bits until next weekend. If you PM me closer to next weekend to remind me, I can have a look through and see what I can dig out.

You are an absolute diamond! I'll happily pay you for whatever you have, and if you won't accept any monetaries, then let me know if there's anything you're needing.. You never know, I may just have it.

If anyone who's built this has bought excess of some or all of these components, I'd be happy to trade or buy your spares. Preferably from one source to save postage, but I don't mind either way, just as long as I get this up and running. Please PM if you can help out.

There was one question about this though, how to match a PNP with a NPN? And if neither the tempco or transistors are thermally coupled (and therefore not actually doing anything), could this be substituted with a fixed metal film & unmatched transistors?

Many thanks in advance...

Hi:
I didn't have any spares, but...
I used 2N3906 instead 2N5910.
I used 680pF Polyestyrene, with 1000pF the frequency will be lower and with 470pF will be higher, but I think will usable in both cases. Don't use polyester here, use a temperature stable cap (polyestyrene, polycarbonate, mica, etc).
I didn't matched the 2N3904 and 2N3906 of the expo pair, and the tracking is very good.
I used 2K Tempcos. I didn't any extensive temperature tests, but seem to work OK. I don't think is good idea to use a metal film instead of the Tempco._________________Sebo
---------------------------------------
My Music:
www.cosaquitosenglobo.com.arwww.myspace.com/cosaquitosenglobo

I have a few left over bits and bobs from my build, including the elusive 2N5910 that you can have. I'm away from where I keep my electronics bits until next weekend. If you PM me closer to next weekend to remind me, I can have a look through and see what I can dig out.

You cannot post new topics in this forumYou cannot reply to topics in this forumYou cannot edit your posts in this forumYou cannot delete your posts in this forumYou cannot vote in polls in this forumYou cannot attach files in this forumYou can download files in this forum

Please support our site. If you click through and buy from our affiliate partners, we earn a small commission.